65V, 8A low-IQ synchronous step-down converter

The LM656x0 is a synchronous buck DC/DC converter offered from a family of

devices with mitigated interference and noise technology using architecture 1

features (MINT 1) that enable low EMI, high power density, and excellent conversion

efficiency. Integrated power MOSFETs with low RDS(on) enable up to 8A of

output current across a wide VIN range of 3.5V to 65V.

Phase stackable with synchronized

interleaving, the peak current-mode control architecture of the LM656x0 supports accurate current sharing with

paralleled phases for higher output currents. AUTO mode enables frequency foldback

during light-load operation, giving high light-load efficiency and a no-load input

current as low as 2.2µA, which extends operating run-time in battery-powered

systems.

A high-side switch minimum on-time of

36ns facilitates large step-down ratios, enabling the direct conversion from 24V or

48V inputs to low-voltage rails

for reduced system cost and complexity. The package has several NC pins between

critical power pins, which improve the Failure Modes and Effects Analysis (FMEA)

result.

The LM656x0 includes several features to simplify

compliance with CISPR 11 and CISPR 32 emissions requirements.

First, a symmetrical pinout provides excellent input capacitor placement and enables

an ultra-low effective value for the power-loop parasitic inductance, which reduces

switching losses and improves EMI performance at high input voltage and high

switching frequency. A pin-selectable switch-node slew-rate control feature further

reduces emissions at high frequencies. To lower input capacitor

ripple current and EMI filter size, interleaved operation using a SYNCOUT signal

with 180° phase shift works well for cascaded, multichannel or multiphase

designs. Resistor-adjustable switching frequency as high as 2.2MHz can be

synchronized to an external clock source to eliminate beat frequencies in

noise-sensitive applications. Finally, the LM656x0

has dual-random spread spectrum (DRSS), a unique EMI-reduction feature that combines

low-frequency triangular and high-frequency random modulations to mitigate

disturbances across lower and higher frequency bands, respectively.

Additional

features of the LM656x0 include 150°C maximum

junction temperature operation, open-drain power-good (PG) indicator for fault

reporting and output voltage monitoring, precision enable input for input UVLO

protection, monotonic start-up into prebiased loads, dual-input VCC bias

subregulator powered from VIN or BIAS, hiccup-mode overload protection, and thermal

shutdown protection with automatic recovery.

The LM656x0

comes in a 4.5mm × 4.5mm, thermally enhanced, 26-pin eQFN

package with additional pin clearance for increased reliability. Also included are

wettable-flank pins to facilitate optical inspection during manufacturing.

Leveraging a flip-chip routable leadframe (FCRLF) packaging technique, the LM656x0 with useable current, lifetime reliability,

and cost advantages targets applications requiring high power density. The wide

input voltage range, low quiescent current consumption, high-temperature operation,

cycle-by-cycle current limit, low EMI signature, and small design size provide an

excellent point-of-load regulator design for applications requiring enhanced

robustness and durability.